ABSTRACT This implementation research project aims to adapt and evaluate a health systems intervention designed to reduce drop-offs in the pediatric HIV cascade (testing, linkage to care, treatment initiation, and viral suppression). Pediatric HIV infection has high morbidity and mortality; prompt diagnosis, linkage to care, and treatment are critical. However, completion of all steps of the pediatric HIV cascade is low, limiting the potential health benefits for HIV-infected children. Provider initiated testing and counseling (PITC) and index-case testing (testing children of HIV-infected adults) are potentially high yield case-detection strategies but are inconsistently implemented with variable coverage. While timely linkage to care and ART initiation are urgent for children, systems to promote and document linkage following diagnosis are weak and pediatric treatment levels lag behind adults. Finally, viral load monitoring is superior to CD4 testing, particularly for children, but systems for prompt and consistent viral load testing and return of results are weak. The pediatric HIV cascade is similar to the PMTCT cascade, having both complex populations and complex systems. Interventions that have been effective at decreasing drop-off in the PMTCT cascade may be effective in optimizing the pediatric HIV cascade. In this study, we aim to adapt and test the Systems Analysis and Improvement Approach (SAIA) intervention which joins classical systems engineering methods including cascade analysis, process mapping, and continuous quality improvement, and which has been effective in improving flow through the PMTCT cascade. In the current R34 proposal, we aim to 1) adapt the SAIA intervention for the pediatric HIV cascade (SAIA-PEDS intervention), 2) pilot and refine the SAIA-PEDS intervention using a mixed-methods approach, and 3) prepare the materials required for a future cluster randomized trial to determine SAIA-PEDS effectiveness and cost-effectiveness. In both this R34 pilot and the future R01 application, our primary outcomes for improvement are a) uptake of pediatric HIV testing, b) linkage to HIV care, c) ART initiation, and d) viral load monitoring and suppression. This project leverages a >25 year collaboration between University of Nairobi and University of Washington collaborators as well as partnerships with the Kenyan National AIDS and STI Control Programme (NASCOP). This unique partnership between academia and policymakers allows rigorous and impactful research to address questions aligned with local priorities that inform national policy.